A federal judge ruled Wednesday that a lawsuit against the Tarrant Regional Water District involving the extended terms of two board members should be heard in state district court first.

The Rev. Kyev Tatum and several relatives sued in federal court last month, saying that they were denied the right to vote and that their constitutional rights were violated when the Legislature changed the water board election date from even- to odd-numbered years. In effect, that extended the terms of board members Marty Leonard and Jim Lane from four to five years.

The suit also said the water district violated the Texas and U.S. constitutions by moving the election to 2015.

It asked a federal judge to order the district to put the two seats on the May 10 ballot. Feb. 28 is the deadline to call elections for May 10.

In his ruling, U.S. District Judge Reed C. O’Connor wrote, “The Court finds an unsettled issue of state law.” He cited precedent that “a federal court should abstain from exercising its jurisdiction when difficult and unsettled questions of state law must be resolved before a substantial federal constitutional question can be decided.”

The “unsettled issue” is whether a House bill setting Tarrant water board elections for May of odd-numbered years conflicts with the Texas Constitution.

The case can return to federal court after the state district court rules, O’Connor wrote.

John Basham, who ran unsuccessfully for the water board, filed a similar suit in 48th District Court. A hearing is set for 3:30 p.m. Thursday.

Matthew Rinaldi, an attorney for Basham and Tatum, said he was “disappointed” with O’Connor’s ruling.

In an emailed statement, a water district spokesman said: “We are pleased with this order, which supports TRWD’s position that this is not a federal constitutional issue. This is a matter of state law, which should be resolved in state court.”

Two years ago, the water district moved board elections from 2012 to 2013 after the Legislature changed the law allowing entities such as school districts to change their elections to the uniform election date in May.

But in the 2013 legislative session, a bill authored by Rep. Charlie Geren, R-Fort Worth, set water district board elections for May of odd-numbered years but did not specifically say that Leonard and Lane could serve beyond their four-year terms.

“It is our intent to hold the election as directed by state law, and we look forward to defending that position in state court,” the water district spokesman said.